The central nervous system (CNS), and the brain in particular, perform some of the most complex and essential processes in the human body. In many cases, however, contemporary health care lacks sophisticated tools to objectively assess brain function. A patient's mental and neurological status is typically assessed clinically by an interview and a physical exam. A typical clinical laboratory currently has no capacity to assess brain function or pathology.
Brain imaging technologies, such as computed tomography imaging (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and single photon emission computerized tomography (SPECT) are widely used and useful, however, these technologies are limited in their ability to provide information about brain function, especially at the early stages of acute care situations. These limitations may be especially significant after trauma has occurred because the brain can require immediate attention to avoid further deterioration.
Many current imaging technologies, when used immediately following an acute brain injury, stroke, diffuse axonal injury (DAI), or seizure, may not reveal any abnormality in the brain even when there is dramatically abnormal brain function. CT and MRI may only detect the condition after the morphology or structure of the brain has changed. In some cases it can take from hours to days after the patient is present in an emergency room (ER) before overt changes are evident on the CT or MRI, and before severe neurological pathology is visible. Electrical activity of the brain, however, is affected immediately.
All of the brain's activity, whether reflexive, automatic, unconscious, or conscious, is electrical in nature. Through a series of electrochemical reactions, mediated by molecules called neurotransmitters, electrical potentials (voltages) are generated and transmitted throughout the brain, traveling continuously between and among a myriad of neurons. This activity establishes the basic electrical signatures of the electroencephalogram (EEG) and creates identifiable frequencies that have a basis in anatomic structure and function. Understanding these basic rhythms and their significance makes it possible to characterize the EEG as being within or beyond normal limits. At this basic level, the EEG serves as a signature for both normal and abnormal brain function.
The electrical activity of the brain has been studied extensively for decades, and especially since the advent of computers. “Normal” electrical activity of the brain has been well characterized in hundreds of studies, with a narrow standard deviation. The electrical activity of some parts of the brain that is a normal response to certain stimuli, such as acoustic, visual, or sensory stimuli, is known as an “evoked potential.” Evoked potentials (EP) are particular waves that have characteristic shapes, amplitudes, durations of peaks within the wave shapes, and many other features, all of which have well established normative data generated over decades of research. Normative data for all of the EEG and evoked response waves are remarkably constant across different genders, ages, and ethnicities. Moreover, any variability that does exist is well described and explained.
Neuroscientists have also characterized the EEG signature of various different brain pathologies. Just as an abnormal electrocardiogram (ECG) pattern is a strong indication of a particular heart pathology, an irregular brain wave pattern is a strong indication of a particular brain pathology. A wide array of pathologies have been well characterized: acute and chronic, structural, toxic, metabolic, and even specific diagnoses such as: ischemic stroke, epileptic seizures, concussion, alcohol, and drug overdose, psychiatric conditions, and dementias including Alzheimer's disease. A large body of data, with continuing refinements and contributions, constitutes the field of clinical neurophysiology.
Even though EEG-based neurometric technology is accepted today and a tremendous body of data exists, application in the clinical environment is notably limited. For example, standard EEG equipment includes an array of electrodes that is placed onto the scalp of a patient. The array usually includes 19 or more electrodes that are placed directly onto the scalp of the patient (often with a conductive gel or paste) or fitted onto the patient using a cap or net. Applying the array of electrodes, each with its own lead wire, can be tedious and time consuming. The wires of the electrodes can also easily become tangled and may interfere with other operations. Furthermore, some equipment used for evoking potentials (e.g., strobe lights, etc.) may be too bulky or may be inappropriate for certain situations. Thus, current EEG equipment and electrode arrays are often not practical for the ER, operating room (OR), intensive care unit (ICU), first response situations, sporting events, or other settings and situations.
The current disclosure is directed to overcoming one or more of the aforementioned problems.